The present invention relates in general to endoscopic surgery, and in articular, to trocars having shields or protectors for use in endoscopic surgical procedures.
The use of endoscopic procedures in surgery has become widely accepted. The term endoscopic as used herein is defined to include all types of minimally invasive surgical procedures including laparoscopic and arthroscopic procedures. Accordingly, numerous endoscopic instruments have been developed which allow the surgeon to perform complex surgical procedures with minimal incisions into the skin and tissue surrounding a particular body cavity or anatomical region. In order to introduce the endoscopic instrumentation into the body cavity, it is often necessary to puncture and cannulate the body cavity by using a trocar. Trocars are widely known in the art and typically consist of an obturator and a trocar cannula. It is common for a sealing arrangement or seal assembly to be used in association with the cannula to prevent the escape of fluid or gas during endoscopic procedures. Trocars may have a protective element around the obturator which covers the sharp piercing tip of the obturator prior to and after insertion, and also after removal of the obturator and trocar cannula. The protective element is often referred to as a safety shield or protector.
One type of trocar utilizes a safety shield and is typically inserted by pressing the distal end of the trocar assembly against the outer skin of the patient with sufficient force to cause the piercing end of the obturator to pierce through the skin, underlying fat, muscle and fascia into the body cavity. The trocar is permitted to penetrate into the body cavity because the safety shield is retracted proximally thereby exposing the sharp piercing tip. However, upon completing the penetration, the safety shield automatically returns to its protective position covering the piercing tip. This type of trocar is a fully returnable safety shielded trocar. Once the surgeon has properly positioned the trocar within the body cavity, the obturator together with the safety shield are removed and the trocar cannula is then available as a pathway, e.g., for insertion of endoscopic instrumentation. U.S. Pat. No. 5,387,197 (Smith et al.) describes this type of trocar.
With current fully returnable safety shielded trocars, it may be necessary to remove the cannula handle from the obturator handle to "reload" the shield on the trocar obturator for those instances where the trocar has not completely penetrated into the body cavity. In this fashion, therefore, it is necessary to perform an extra step while the obturator tip is inserted within pneuoperitoneum.
Yet, in some procedures it may be desirable to utilize trocars without a safety shield or to utilize a trocar design wherein the trocar obturator is nonshielded at the time when the trocar obturator is placed within the trocar cannula. Thus, upon coupling of the shielded obturator and the cannula, the shield will be retracted thereby exposing the piercing tip of the obturator. This type of trocar can be referred to as an assembly actuated trocar.
An assembly actuated trocar prevents the shield from returning to its protective position upon placement of the obturator within the cannula. U.S. Pat. No. 5,248,298 (Bedi et al.) describes this type of trocar. In this way, the user is able to slightly withdraw the trocar from the pierced tissue, and then continue penetrating through remaining tissue layers. This prevents what is commonly referred to as "tenting" of pneumoperitoneum. In this fashion, tenting can be reduced while still adequately providing access to the body cavity.
In an effort to eliminate problems with tenting or to reduce cost from surgery, surgeons often utilize trocars that do not employ a safety shield since these types of trocars are generally less expensive than fully returnable safety shielded trocars. However, for those procedures that utilize trocars without a safety shield, there is a possibility that the obturator tip could cut a person handling the trocar or damage the trocar seal assembly or other components of the instrument.
Presently, there is no known trocar that provides a low cost option to the surgeon while maintaining the ability to protect the obturator piercing tip with a shield or protector up until the time when the obturator is coupled to the proximal end of the cannula.